Watermom, he's got an Intex -- those can be drained safely.

Rock, it's been a long week, and I wasn't paying attention either. If you drain and refill, you can do just as you say, and will not need floc.

Watermom is also correct that you probably don't need to CHANGE your sand -- unless it's tacky/sticky or in clumps -- you just need to top it off.

Sorry!